Posted by: Mark Polk | 2016

Jeep CJ7 Squealing Belt Fix

pulley finishedThis article is for the V-belt on a 1981 Jeep CJ7. The jeep does not have a serpentine belt and it does not have an automatic belt tensioner. Belts on an engine are used to power essential items and accessories like the alternator, power steering or air conditioning. My 81 CJ7 has a 2.5L engine and there is only one belt. The Jeep does not have accessories like power steering or air conditioning so the single belt is  used for the alternator, water pump and cooling fan.

About a year ago I drove the Jeep through some fairly deep water during a thunderstorm and shortly afterwards I had to replace the alternator. Prior to that the belt rarely made any noise. After replacing the alternator the Jeep developed an ongoing problem with a squealing belt.

Belts can squeal for several reasons. The belt can slip on the pulley, it can be out of alignment, the belt tension can be out of adjustment and the belt or the pulley(s) can be old and worn out. My first attempt at fixing the problem was to adjust the belt tension.  In the military we would simply press our thumb in the center of the belt, between two of the pulleys, and if there was 1/2 inch to one inch of deflection it was within adjustment. After I adjusted the belt it continued to squeal every now and then.

My next attempt at correcting the problem was checking and adjusting the belt alignment. It looked as though the belt might be slightly out of alignment, so I used washers between the alternator and the bracket until the belt looked perfectly in line with the pulleys and the alternator. After correcting the alignment the belt still squealed periodically.

belt glazedMy third attempt at fixing the noisy belt was to remove and inspect the belt and the pulleys. What I discovered was the belt and the pulleys were glazed. My thought was the heavy glazing probably caused the belt to slip, making the squealing noise.



pulley sandedI rolled up a piece of sandpaper so it fit in the groove of the pulleys and sanded both pulleys unit the glaze and rust was removed down to bare metal.




pulley paintedI bought a can of black high-heat engine spray paint and painted two coats on both pulleys. I wanted to make sure the paint had plenty of time to dry and cure before testing it, so I let it sit for 48 hours.

I bought a new v-belt, installed it, adjusted it and started the Jeep. No squealing. I drove the Jeep and there was no more squealing. Problem solved. I just wish I checked the belt and pulleys first!


Mark Polk

Auto Education 101


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